MMP POLYURETHANE INTERMIX The MMP Polyurethane Intermix is an amazing product. You may ask; DO I NEED IT ? Yes and No. MMP Poly is optional. As modelers we highly recommend it. The poly does a few things. It increases flow from the airbrush in addition to the incredible non-clogging flow you get with-out. Slower drying times, increased durability and adds a beautiful slight eggshell sealed sheen plus a flawless smooth finish. The Poly Intermix is also an additional adhesion promoter and increases durability. The natural eggshell finish is ideal for many reasons. Seals the paint for washes, pin washes, applying decals and more. Poly is not a flow enhancer. Flow is just one of the by products and features of the poly. Adding poly will create an automotive grade polyurethane based acrylic paint that is tough as nails.